Can't alter Route of created Page

Can't alter Route of created Page.
Also it is absent in list of existing routes on altering process:

services:
  example.route_subscriber:
    class: Drupal\example\Routing\RouteSubscriber
    tags:
      - { name: event_subscriber }

I found Event PaggeManagerContextEvent.

But what is format for $condition:
Page::addAccessCondition($condition) ?
For example: How can I check if current_user is same as Page argument user?